package sm3

import (
	"hash"

	gmsm3 "github.com/emmansun/gmsm/sm3"
)

type SM3 struct {
	h hash.Hash
}

func New() hash.Hash {
	s := &SM3{}
	s.Reset()
	return s
}

func (sm3 *SM3) BlockSize() int { return gmsm3.BlockSize }

func (sm3 *SM3) Size() int { return gmsm3.Size }

func (sm3 *SM3) Reset() {
	sm3.h = gmsm3.New()
}

func (sm3 *SM3) Write(p []byte) (int, error) {
	if sm3.h == nil {
		sm3.Reset()
	}
	return sm3.h.Write(p)
}

func (sm3 *SM3) Sum(in []byte) []byte {
	if sm3.h == nil {
		sm3.Reset()
	}
	return sm3.h.Sum(in)
}

func Sm3Sum(data []byte) []byte {
	sum := gmsm3.Sum(data)
	out := make([]byte, len(sum))
	copy(out, sum[:])
	return out
}